This invention relates generally to systems and methods for electrophoretic separati ly to improvements in continuous flow electrophoretic separation systems and methods.
Electrophoresis is a commonly used technique for separating minute quantities of small particles or macromolecules for analyses or characterization. Conventional approaches involve batch systems which are not capable of separating large or even significant quantities of the materials. To use electrophoresis for separating large quantities of materials to prepare useful and marketable quantities of separated materials, it is necessary to employ a means of continuous flow electrophoresis. Various systems and methods have been proposed to facilitate continuous electrophoresis separation in various flow-through systems of either a stationary free flow type or moving wall (usually continuous belts) type or single rotating cylindrical wall type. In each of these devices, a buffer, or carrier, liquid is introduced at one end of a thin cross section chamber and drawn off at the other end to create a flowing curtain of liquid between a pair of electrodes of opposite polarity forming at least a portion of the confining walls of the chamber. By applying a voltage to the electrodes, an electric field is formed in the chamber transverse to the direction of flow in the chamber. A sample stream containing a mixture of various components capable of electrophoretic separation is injected into the buffer stream so that it flows through the chamber. As the sample is carried through the chamber, each component of the sample migrates toward the oppositely charged electrode a distance which is dependent upon the size of the component, the viscosity of the carrier liquid and the magnitude of the component charge. This causes like components of the sample to form into bands in the buffer stream across the width of the chamber between the electrodes. These separate bands of differing components are collected at the exit end of the chamber by means of zoned exit ports whose total flow is commensurate with the total flow of the sample and carrier.
Although various systems have been devised to compensate disruptive dynamic flow patterns in the chambers of flow-through systems due primarily to flow perturbations created from either containment wall frictional flow (Poiseuille flow) and/or electroosmosis due to the wall zeta potential, the known systems either add increasing complications to the design or operation of the flow system, making them ineffective for continuous flow production systems. These two flow disturbances combine in conventional electrophoretic separation devices to produce crescent-shaped flow distortion of the separated components in the otherwise laminar flow stream, making it difficult to collect the separated components at the different exit zones of the flow system. Accordingly, it will be appreciated that there is a need for an improved system and method of continuous flow electrophoresis.